Laminated metal plates

ABSTRACT

Laminated metal plates made of (1) an outer layer of a metal, (2) an intermediate layer of a polymer, (3) an inner layer of a metal, (4) an intermediate layer of a polymer and (5) an outer layer of a metal. It is a characteristic of the invention that the polymer of layers (2) and (4) is a special terpolymer.

United States Patent Mueller-Tamm et al.

LAMINATED METAL PLATES Inventors: Heinz Mueller-Tamm, Ludwigshafen;Alired Hofmann, Roxheim, both of Germany Assignee: Badlsche Anllin- &Soda-Fabrlk Aktlengesellschaft, Ludwlgshnfen Rhine. (lurmtmy Filed: May19, 1969 Appl. No.: 825,929

Foreign Application Priority Data 15] 3,655,504 [451 Apr. 11, 1972 [56]References Cited UNITED STATES PATENTS 3,201,374 8/1965 Simms ..260/80.83,249,570 5/1966 Potts et al. ..260/80.8 3,312,676 4/1967 Rees..260/80.8l 3,352,742 11/1967 Zunich et a1 161/216 3,382,136 5/1968Bugel et a1. ....161/2l6 3,455,775 7/1969 Pohl et al 161/217 3,475,24010/1969 Manaka et al. ..161/214 3,481,812 12/1969 Holubetal. ..161/216Primary Examiner-John T. Goolkasian Attorney-Johnston, Root, OKeeffe,Keil, Thompson & Shurtleff [57] ABSTRACT 1 Claim, No Drawings LAMINATEDMETAL PLATES The present invention relates to laminated metal platesmade up of:

1. an outer layer of metal having a thickness of from 0.005 to 0.5 mm; A

2. an intermediate layer of a thermoplastic polymer having a thicknessof from 0.02 to 1.5 mm;

3. an inner layer of ametal having a thickness of from 0.3 to 4 mm;

4. an intermediate layer of a thermoplasticpolymer having a thickness offrom-0.02m 1.5 mm; and

5 an outer layer of a metal having a thickness of from 0.005 to 0.5 mm.

Known metalplates of this type generally contain as the intermediatelayers (2) and (4) of a 'themioplastic polymer layers of apolyamide,polyester or copolymer of ethylene and vinyl acetate, acting as ahot-melt adhesive. The individual layers of these plates have a fairlygood resistance to peeling with respect to each other, but a relatively.poor resistance to tensile shear stress.

Moreover, laminated metal plates are known which contain as theintermediate layers (2) and (4) adhesives known as contact adhesives,for example those based on polyisobutylene, polyacrylic esters ornatural rubber, i.e. polymeric substances which at room temperature arepermanently plastic and adhere very well to metals. These plates havenot only the abovementioned disadvantage of fairly poor resistance totensile shear stress but also the disadvantage that their creep rupturestrength and resistance to high temperature leave much to be desired.

Furthermore, laminated metal plates are known having fairly goodresistance to tensile shear stress, relatively good creep rupturestrength and fairly good resistance to high temperatures. In theseplates the intermediate layers (.2) and (4) consist of an adhesive knownas a two-component adhesive, i.e. generally an epoxide resin, polyesterresin or polyurethane resin. It is a disadvantage of these plates thatthey have a relatively poor resistance to peeling.

The object of the present invention is to provide laminated metal platesof the abovementioned type which do not have the abovementioneddisadvantages or have them to a' considerably smaller extent.

We have found that this object is achieved when the intermediate layers(2) and (4) consist of a special thermoplastic terpolymer.

The present invention accordingly consists in a laminated metal platemade up of:

1. an: outer layer of metal having' a 'thickness of from 0.005 to :5mm;

2. an intermediate layer of a thermoplastic polymer having a thicknessof0=02 to 1.5 mm;

3'. an inner layer of a metal having a thickness'of 0.3 to 4 mm;

4. an intermediate layer of a thermoplastic polymer having a thicknessof from 0.01 to'l.5 mm; and

5. an outer layer of a metal having a thickness of from 0.005

to 0.5 mm. The metal plates according to this inventionare'characterized by the fact that the thermoplastic polymer of layer(2) and layer (4) is a terpolymer consisting of 60 to 90 percent byweight of ethylene units, 0.5 to 20 percent by weight of units of anethylenically unsaturated carboxylic acid and 0.5 to 20 percent byweight of units of an ester'of an ethylenically unsaturated carboxylicacid.

It has been found that the metal plates in accordance with thisinvention have particularly favorable properties when the thermoplasticpolymer of thelayers (2) and (4) is a terpolymer consisting'of 7l to 90percent by weight of ethylene units, 3 to 9 percent by weight of unitsof an aliphatic'ethylenically unsaturated C to C carboxylic acid, and lto 20 percent by weight of units of a C to C alkyl'ester of an aliphaticethylenically unsaturated C to C carboxylic acid.

It has been found that the favorable properties of metal platesaccording to this inventionare especially evident when -2 thethermoplastic polymer of the layers (2) and (4) is a terpolymerconsisting of 71 to percent by weight of ethylene units, 3 to 9 percentby weight of acrylic acid units and l to 20 percent by weight oftertiary-butyl acrylate units.

The outer metal layers (1) and (5) for the plates in accordance withthis invention may be layers (foil or sheeting) of the conventionalmetals, particularly of copper, brass and stainless steel. Layers ofprecious metals such as silver and gold may also be used because thelayers in question do not have any load-bearing or stiffening functionand may therefore be of any thinness. The metal layers l) and (5) in theplates-according to this invention may be of equal or differentthickness and may consist of the same or different metals.

The terpolymers to be used in accordance with this invention for theintermediate layers (2) and 4) are known as such from polymer chemistry.They should advantageously have the following characteristic data:density from 0.9 to 1.1 g/cm; crystalline fraction less than 60 percent;Shore Hardness C from 50 to 90. In the metal plates, the terpolymers oflayers (2) and (4) may be identical or different in their composition.The terpolymers are advantageously used in the form of film or sheeting.Since they act as a kind of thermoplastic adhesive, they should bepresent during processing (i. E. in the manufacture of the metal plates)in the plastic to viscous condition. They are used at temperatures offrom 80 to 250 C particularly from to 220 C.

The inner metal layer (3) may be a layer (sheet) of a conventionalmetal, particularly aluminum or steel. The thickness of this layershould preferably be such that it determines to a predominant extent thedesired flexural stiffness or dimensional stability of the metal plate.

The production of the plates according to this invention may be carriedout by conventional methods, for example by placing in a press, oneabove the other, a metal foil or sheet (to form layer (1)), a film orsheet of the terpolymer (to form layer (2)), a sheet of metal (to formlayer (3)), a film or sheet of the terpolymer (to form layer (4)) and ametal foil or sheet (to form layer (5)), after which pressure is appliedat elevated temperature.

The laminated metal plates obtained are suitable for example as exteriorwall panels and as structural or decorative elements inautomobile, shipand machine construction.

The invention is illustrated by the following Example.

EXAMPLE A copper foil having a thickness of 0.1 mm (to form layer (1))is laid in a press, anda film having a thickness of 0.2 mm andconsisting of a terpolymer containing 88.3 percent by weight of ethyleneunits, 3.5 percent by weight of acrylic acid units and 8.2 percent byweight of tertiary-butyl acrylate units (to form layer (2)) is laid onthe copper foil. A steel sheet having a thickness of 2.2mm (to formlayer (3)) is then laid on, followed by a 1 mm thick sheet of aterpolymer containing 81.1 percent by weight of ethylene units, 17.6percent by weight of acrylic acid units and 1.3 percent by weight oftertiary-butyl acrylate units (to form layer (4)). Then a copper foilhaving a thickness of 0.1 mm (to form layer (5)) is laid on and thewhole is pressed at a temperature of C. and a pressure of 0. 15 g/cm for5 minutes to form a laminate. The laminated metal plate obtained isremoved from the press at a temperature of 70 C. and allowed to cool toroom temperature without any pressure being applied.

We claim: 1. A laminated plate made up of: 1. an outer layer of copper,brass, stainless steel, silver or gold having a thickness of from 0.005to 0.5 mm;

2. an intermediate layer of a thermoplastic polymer having a thicknessof from 0.02 to 1.5 mm;

3. an inner layer of aluminum or steel having a thickness of 0.3 to 4mm;

4. an intermediate layer of a thermoplastic polymer having a thicknessof from 0.01 to 1.5 mm; and

5. an outer layer of copper, brass, stainless steel, silver or goldhaving a thickness from 0.005 to 0.5 mm, wherein the thermoplasticpolymer of layer (2) and layer (4) is a terpolymer consisting of 60 to90 percent by weight of ethylene units, 0.5 to 20 percent by weight ofacrylic acid 5 units, and 0.5 to 20 percent by weight of tertiary-butylacrylate units.

2. an intermediate layer of a thermoplastic polymer having a thicknessof from 0.02 to 1.5 mm;
 3. an inner layer of aluminum or steel having athickness of 0.3 to 4 mm;
 4. an intermediate layer of a thermoplasticpolymer having a thickness of from 0.01 to 1.5 mm; and
 5. an outer layerof copper, brass, stainless steel, silver or gold having a thicknessfrom 0.005 to 0.5 mm, wherein the thermoplastic polymer of layer (2) andlayer (4) is a terpolymer consisting of 60 to 90 percent by weight ofethylene units, 0.5 to 20 percent by weight of acrylic acid units, and0.5 to 20 percent by weight of tertiary-butyl acrylate units.